Despite continuing volatility in commodities prices, the seismic crews just keep going, acquiring data in numerous locales around the globe.
Currently, the working crew tally stands at 305 worldwide with 85 crews still available, according to the mid-January issue of World Geophysical News (WGN).
In comparison, the numbers reported in WGN last July 15 came in at 277 and 98 respectively.
Once again, the United States leads the pack with 76 active crews, or 25 percent of the total, with neighboring Canada accounting for 23 crews, or 8 percent.
The remaining 206 active crews are scattered far and wide in various countries, where myriad challenges for the seismic data gatherers can include cultural, logistical and governmental issues.
Additionally, there are the usual problems indigenous to seismic surveys, such as difficult-to-navigate terrain, noise-rendering infrastructure and more.
A Passage to India
Look at India, for instance, where Global Geophysical Services kicked off a shallow-water, 1,000-square-kilometer 3-D survey in January for client ONGC. The seismic program is concentrated in the Gulf of Khambhat on the western coast of India, southeast of the Kathiawar Peninsula.
“It’s one of the most challenging shallow marine areas in the world,” said AAPG member Richard Degner, president of Global, which currently has half of its 14 crews working the international scene. “There are six meters of tidal change and three-to-four-knot currents associated with those tidal changes that rip in and out of the Gulf of Khambhat into the Indian Ocean.
“The ocean bottom cables have to be specially designed so we can deploy them down to the bottom so they stick and don’t get blown around in these extreme currents.”
A number of modifications were required to accommodate the currents. These included constructing metal frames for the sensor package to lay on when the cable is deployed. These frames keep the receivers in place and ensure there is no movement once the receiver hits the seafloor.
“Another challenge with the currents is that they generate noise, especially on the geophone,” said Larry Scott, Global’s vice president for worldwide marine. “A three-knot current going over the geophone will shake the casing and generate a signal.
“We’re working closely with our data processing technology partner, Weinman GeoScience, on various noise attenuation techniques to allow data acquisition to continue in higher current flows than normally practical.
“This is a very intense survey,” Scott noted, “with extremely high specifications in terms of both seismic and positioning data quality.”
To add to the Khambhat challenges, the nearest port for moving gear and personnel back and forth to the crew is the tidal port of Surat, where boats may have access only twice daily.
The plan is for the crew to work until the monsoon season, which runs from the start of June through September, and then rev back up in October with the goal of calling it a wrap in the spring of 2009.
Assembling the vessels needed for the India survey was in itself a daunting task.
Eight vessels are working there, including Global’s flagship transition zone boats from the United States – the Vision and the Quest. These are joined by the mother ship chartered out of Singapore and a couple of speedboat-like shallow draft aluminum jet-drive boats from Australia, which were modified to be especially effective at moving cable in strong tides and currents.
The source and support vessels were chartered out of Dubai, where Global has a support base to rig its land crews.
“Most of the recording gear was new and shipped out of Houston and Europe,” Degner said. “Everything converged in India, and we spent two months getting the crew all rigged out and finalizing permissions.”
Still, “expect the unexpected” remains the motto when deploying crews on the international scene.
When Global shipped the gear out of Houston last August for a planned shoot in Kurdistan, a bit of angst ensued.
“The gear headed to the Mediterranean for a port in Turkey where it then would skirt along the Turkish border by overland convoy headed for northern Iraq,” said Maurice Flynn, vice president for Europe and Middle East at Global.
“Soon after we loaded the equipment on the boat in Houston, all the border skirmishes between Turkey and Kurdistan flared up,” Flynn said. “Based upon its destination, we weren’t sure if the equipment would be discharged at the Turkish port, and if it was whether it could get through to the border and then pass through into Kurdistan.
“As it worked out, we were in Iraq in less than seven days after landing in Turkey and had the crew working two weeks later.”
Northern Iraq: ‘A Different World’
Kurdistan is in a 2-D phase today, given that much of the seismic work in the region is being conducted for exploration purposes.
This is the mindset at WesternZagros Resources, which contracted Global to implement a 500-kilometer 2-D survey in Kurdistan. The project is a mixed source program using vibroseis supplemented with dynamite infill where necessary.
“Our objective is to get as much 2-D seismic coverage as we can to evaluate the potential for hydrocarbon accumulations on our acreage,” said Ke Lovan, staff geophysicist at WesternZagros. The company was spun off from Western Oil Sands (WOS) along with the Kurdistan acreage upon Marathon’s purchase of WOS.
“We hope to identify large features and structures,” Lovan noted. “They’ll be primarily structural traps, with a major stratigraphic component.
“The reservoirs in this region are primarily Tertiary and Cretaceous, and reservoir targets are all over the board as we’re in a fold and thrust belt,” Lovan said. “You have surface seeps of both oil and gas.
“Existing wells have both shallow and deep pay zones,” he said, “with some drilled beyond 5,000 meters.”
The seismic survey kicked off last November and is anticipated to require as much as five months.
Despite the widespread turmoil in Iraq, the oil industry folks are showing increasing interest in operating in this country known to harbor huge oil reserves.
“Before 2007, there were only three oil companies operating there,” Lovan said. “Now there are over 20.”
Security remains a challenge for oil industry personnel in the country as a whole, yet the Kurdistan region itself is not particularly off-putting.
“The northern part of Iraq is quite a different world,” Lovan noted. “Kurdistan itself is a peaceful region that has been semi-autonomous since the early 1990s. Prior to Global, only one seismic company was willing to set up shop in northern Iraq to run a seismic program.”
For anyone contemplating a seismic project there, it may be reassuring that Degner refers to Iraq as a “piece of cake” compared to some other international surveys they’ve done.
Degner gives kudos to Oman as well, where Global is ramping up a brand new crew for a 2,800-square-kilometer 3-D program for BP.
“Oman being in the Arabian Peninsula with proximity to Dubai provides the ability for support within the Gulf Emirates,” Degner said. “So it’s a pretty easy place to execute into and operate in.
“This is a very large channel count survey, a 10,000 channel Sercel 428 shoot,” he noted. “The crew has 12 80,000-pound vibrators with the new Sercel 464 vibe electronics, all shipped over from Houston. This project is one of the new ultra-progressive Vibroseis applications.”
It’s a survey with a very high trace density, Flynn said – and the largest single 3-D survey recorded in Oman.
Preparation is Crucial
The multitudinous pieces that must come together to make one of these international crews a reality can be a bit mind-boggling.
In fact, Degner cautions that if you want to pursue work a year from now, it’s prudent to begin preparations today.
“It takes that long to manufacture, build and deploy all those assets,” he said. “When these deployments happen, we have the group in Houston that gets all the recording gear, the huge vibrators and other technology together.
“Then it’s the local guys – like for Oman, our Dubai-based group – who build the camps locally and purchase the trucks.
“In fact, for both the Middle East and North Africa, we typically build our camps for several hundred people out of Dubai, purchase the trucks in Dubai and build the trailers,” he said. “There may be a hundred pieces of trucks and camps, including rolling stock, that goes into these big vibroseis jobs especially.
“For Iraq there may be only 50 or 60 pieces, like camp trailers and trucks,” Degner said. “For our survey in the Nuequen Basin in Argentina, we have about 80 or 90 pieces of camp and rolling stock.
“When these mobilizations occur, we buy all new equipment – including the support equipment – locally,” he noted. “This includes trucks ranging in size from big semi-trucks to pickups, each with a different application such as hauling water, food, personnel.
“It’s more cost-efficient, and you can support the equipment better if it’s purchased in the local economy,” Degner noted.
“The tax regime usually requires it, anyway.”